You’re likely using more than 10% of your brain power

A: In “Lucy,” the new movie about a woman (Scarlett Johansson) whose brainpower is enhanced by drugs, Professor Norman lectures: “It is estimated most human beings only use 10 percent of their brain’s capacity. Imagine if we could access 100 percent. Interesting things begin to happen.”

This image released by Universal Pictures shows Scarlett Johansson in a scene from "Lucy." (AP Photo/Universal Pictures)

Now, I know Morgan Freeman is well versed in playing the wise sage, but professor, I beg to differ. You see, we all access 100 percent of our brains every day. And we don’t have to be telekinetic or memorize an entire deck of cards to do it.

In a way, the idea that we only use 10 percent of our brains may motivate us to try harder or to tap into some mysterious reservoir of creativity and potential. There are even products that promise to unlock that other 90 percent.

As ludicrous as the claim is, however, two-thirds of the public — and get this, half of science teachers — reportedly believe the myth to be true.

How did this misconception come about?

We may be able to track its roots to psychologist William James, who wrote in his 1907 text “The Energies of Men” that “we are making use of only a small part of our possible mental and physical resources.”

I tend to agree with this sentiment when I spend my evenings on the couch watching reality television, but James didn’t intend to lend credence to this 10 percent myth.

Someone else did. Lowell Thomas, in his foreword to Dale Carnegie’s 1936 book “How to Win Friends and Influence People,” reinterpreted the statement and, it seems, sprinkled in a few of his own ideas.

“Professor William James of Harvard,” wrote Thomas, “used to say that the average person develops only 10 percent of his latent mental ability.”

Here’s the thing: The brain has rapidly tripled its original size across 2 million years of human evolution. Despite only accounting for 2 percent of our body weight, the brain gobbles up a whopping 20 percent of our daily energy intake. Our brains are also remarkably efficient, having evolved gyri (ridges), which have dramatically increased our cortical-surface-area-tototal- volume ratio relative to other species.

The “we only use 10 percent of our brains” claim would mean that we’re effectively evolving in the opposite direction — and that we’re doing this very quickly.

Another obvious way we know that we’re using more than 10 percent of our brain at any one time is through approaches like functional magnetic resonance imaging and positron emission tomography. PET and fMRI are imaging techniques that reveal areas of relatively high brain activity in real time.

Imaging studies tell us that not only are many brain areas recruited when performing even the simplest of tasks, like watching a movie, but that the activity between these areas is extremely dynamic.

– Jordan Gaines Lewis

Last modified: August 5, 2014
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